package Leetcode.lc015;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/***
 * 三数之和，双指针
 */
public class Sloution {
    public List<List<Integer>> threeSum(int[] nums) {
        List<List<Integer>> res = new ArrayList<>();
        Arrays.sort(nums);
        for (int i = 0; i < nums.length; i++) {
            //剪枝操作
            if (nums[i] > 0) break;
            //去重
            if (i > 0 && nums[i] == nums[i - 1]) continue;
            int left = i + 1;
            int right = nums.length - 1;
            while (left < right) {
                int sum = nums[i] + nums[left] + nums[right];
                if (sum < 0) left++;
                else if (sum > 0) right--;
                else {
                    //记录保存数据
                    res.add(Arrays.asList(nums[i], nums[left], nums[right]));
                    //去重
                    while (left < right && nums[left] == nums[left + 1]) left++;
                    while (left < right && nums[right] == nums[right - 1]) right--;
                    left++;
                    right--;
                }
            }
        }
        return res;
    }

    public static void main(String[] args) {
        Sloution sloution = new Sloution();
        int[] ints = {-1, 0, 1, 2, -1, -4};
        List<List<Integer>> result=sloution.threeSum(ints);
        for(List<Integer> a:result){
            System.out.print(a);
        }
    }
}
